A young Alberta woman charged with killing her newborn baby in 2005 has been found guilty of second-degree murder.

But the lawyer for 23-year-old Katrina Effert said he plans to challenge the jury's verdict and will apply to have the case declared a mistrial, calling it a "perverse and unreasonable" outcome.

Effert, who admitted to killing her child, had tried to plead guilty to infanticide at the start of the trial, but the Crown rejected the plea. She did plead guilty to disposing of a body in order to conceal it.

Effert had been accused of strangling the newborn hours after she gave birth to him in the basement of her parents' house in Wetaskiwin, Alta., and then tossing his body into the neighbours' yard.

In his closing arguments, Crown prosecutor John Laluk told the jury that Effert wanted her baby dead and strangling her child was "a coldly, coldly brutal act."

Laluk told the jurors Effert was a skilled and manipulative liar and everything she did after the child died was the product of a calculating mind.

But Effert's lawyer, Peter Royal, argued the killing of the child, while abhorrent and appalling, was the result of a disturbed mind, which means his client should instead be found guilty of infanticide.

Royal said it happened because she was alone, frightened and mentally disturbed.

With files from The Canadian Press